Friday, July 3, 2009

This one, at least, is common and perhaps overused, likely for want of other choices. It is certainly a dramatic beauty, with large, glossy leaves and huge, deliciously fragrant white flowers. There are many cultivars, most with intermediate foliage and pyramidal crowns 40-60 ft. tall. Dwarfs like 'Little Gem' are popular for restrained size, though this one sometimes has a problem with fungus that thins the foliage. "Majestic Beauty has the largest leaves, but can be pale and shy-flowering here. 'Bracken's Brown Beauty' and 'D. D. Blanchard' are dense and narrow , with striking rust-brown leaf undersides. Evergreen magnolia is amazingly hardy and adaptable, but trees on dry hardpan may be thin, yellowish and stunted.

Magnolia virginiana v australis/ EVERGREEN SWEET BAY

This harder-to-find magnolia may be a more useful tree in most situations. Smaller, narrower leaves than those of M. grandiflora, silvery below, give it a more intermediate texture. Small, fragrant white flowers open through the warmer months. Most trees reach a narrow 30 ft. or so. Though a swamp tree, it is remarkably drought-hardy. Cultivars such as 'Henry Hicks' are typically evergreen though they may not fall under variety australis. Best to buy M. virginiana in late winter to be sure of its leaf retention.

Maytenus boaria / CHILEAN MAYTEN

Willowy grace is the feature of this small tree. Narrow, 1-2 in. long leaves in bright green make billowy streamers arching from slender branches. Some plants are full and upright, others, especially when older, take on a weeping-willow habit. Mayten tolerates wet soil as well as drought, though it is very slow on dry hardpan. Trees in shade or moist soil may reach 40 ft. while those in tougher circumstances stay 15-20 ft.

Michelia maudiae / SMILING FOREST LILY TREE

As charming as its common name, this small magnolia relative ( now officially a Magnolia, it seems) grows to 20 ft. or so, with glossy, 4-6 in. leaves and large, fragrant white flowers in spring. It is relatively new and scarce in the Northwest, but established trees, seen here and there, have done well and the tree seems hardy in at least our warmer zones. A few street trees in Portland are thriving without water.

Nothofagus dombeyii / COIGUE

Most of the southern beeches, Nothofagus, are tiny-leaved evergreens. This Chilean species captivates nearly everyone with its deep green, 3/4 inch leaves in neat, flat fronds on slender, undulating branches. Young trees race to a height of 80 ft. or more, with many smooth, gray ascending branches. Old specimens in Chile resemble gnarled oaks. The only hangup with these trees, besides rarity in nurseries, is their vulnerability to high winds; a spot where the prevailing winds are filtered is best.

Persea yunnanensis

Related to avocado and other subtropical beauties out of our reach, this rare Chinese tree is hardy in all the warmer Northwest zones. Its lush, rounded crown in made of slender, glossy, aromatic leaves that are silver-blue beneath. Blue, olive-like fruits ripen in fall. The tree reaches 40 ft. or more, drought-hardy and happy in sun or shade.

Photinia serratifolia / CHINESE PHOTINIAPopular in the 1950's and earlier, this handsome tree deserves a comeback. Its large, glossy leaves, open in February and March in glowing shades of golden orange and coppery red. White flowers in wide clusters follow. Dense and round-headed, Chinese photinia reaches 30-50 ft. tall. Once shunned for mildew, it is seldom troubled by it in sunny, unwatered sites. Its hybrid offspring, the ubiquitous P. x fraseri makes a good small tree, too, but is increasingly subject to disease.

Quercus / OAKS

Here is the largest group of broadleaved evergreen trees for this area. At least half of the 600 oak species are evergreen; only a few are readily available though many others are sold by specialty nurseries. Colvos Creek carries many in small sizes.

Quercus chrysolepis / CANYON LIVE OAK

This native of sw Oregon and California has small, holly-like leaves on rather gnarled branches. It reaches 60 ft. or more, with a beautiful framework of smooth, very climbable branches. Bushy when young, it requires some early pruning to establish a straight, clear trunk for urban situations.

Quercus hypoleucoides / SILVERLEAF OAK

From the Southwest and Mexico comes this beautiful and easy-to-grow oak. Slender, tapered leaves are leathery gray green above, velvety white below, very nice in the wind. A layered, pyramidal crown reaches 20-30 ft. rather quickly, eventually topping out at 50-60 ft. This great tree is quite adapted to the Northwest and is thriving, though still rare, around the region.

Quercus ilex / HOLLY OAK, HOLM OAK

This sturdy oak of the Mediterranean region is planted in mild zones around the world and is seen here and there on the streets of Portland and Seattle. Its variable leaves are small, oval to tapered, toothed or not, and deep gray green above, pale below. The crown of a holly oak is usually dense and the trees have sometimes been sheared into formal shapes. Eventually, the tree opens up some and takes on more character. It is very adaptable and drought hardy, but trees brought up from California trained to a stake often have slender, weak stems. Better to take a bushy specimen with stout trunk and gradually prune to the desired form.

Quercus laurifolia / LAUREL OAK

This is perhaps the best broadleaved evergreen tree for streets and other city uses. Its narrow, grass-green leaves on slender branches thin out in winter, letting in light yet retaining a leafy green aspect. It makes a broadly pyramidal crown to 60 ft. tall and adapts to nearly any soil, from wet to dry. Though a native of the South, it is perfectly hardy here.

Quercus myrinaefolia / BAMBOOLEAF OAK

Slow and dignified, this Japanese tree eventually reaches 40 ft. tall with round outline. Narrow, tapered leaves are glossy bright green above, silvery below, and point slightly downward in an elegant pattern. This oak responds beautifully to rich moist soil but manages well in most conditions and is drought hardy once established. Several related Japanese oaks, Q. glauca, Q.acuta, Q. gilva and Q. stenophylla are all good, too.

Quercus suber / CORK OAK

Bottle-stoppers and flooring are made from the bark of this Mediterranean tree. In deep ridges and furrows it covers a beautifully gnarled and angled trunk that carries billows of gray-green, holly-like leaves in an open, 40-80 ft. crown. This is a character tree, best as a specimen, hard to use on streets unless pre-trained to a straight trunk. It is hardy in all warmer Northwest zones.

Sycopsis sinensis

A small tree related to witch hazel, this rather plain plant is never the less pleasing and quite hardy. Narrowly ovate leaves in deep olive green hang gracefully from slender branches to form a not-too-dense, rounded crown. Tiny puffs of orange flowers in winter reward close inspection. Drought-hardy and nearly pest free, the sycopsis shouldn't be so rare. It slowly reaches 20 ft. or so.

Umbellularia californica / OREGON MYRTLE, CALIFORNIA BAY

A native of California and southwest Oregon, Oregon myrtle can be a large shrub on dry hillsides or more often a tree to 80 ft. or more with moisture and better soil. Foliage is similar to that of Laurus, the Mediterranean bay, but more tapered, a bit brighter green and much more wild in aroma. Tiny winter flowers are followed by green, inch-wide fruits with large seeds that sprout readily in the vicinity. This handsome tree needs lots of room -it's hard for many plants to grow in its pungent shade- and the tree can be stunted by clay hardpan.

Thursday, July 2, 2009

I can't stay away from the topic of broadleaved evergreen trees. Deciduous trees are the default setting in the Northwest. Yet in places where there is little but pavement, cars, buildings and worse, we need the softening and color of foliage all the time. Though large expanses of deciduous forest or shrublands are lovely even in winter, a few trees along a downtown street or in a parking lot aren't enough to counteract the cold, gray harshness of an urban scene when they are leafless. We need foliage.

There are several arguments against broadleaved evergreen trees. The most reasonable one is that they block valuable winter sunlight. To avoid that, these trees should be kept away from windows, especially on the south, or trimmed high enough that the low winter sun reaches the window. Also, there are some evergreens with light canopies- laurel oak, for example- that let light through.

Others argue that broadleaved evergreens lose branches in our occasional heavy snows. It seems logical, but trudging through the extended snows of last December, I did not see an extraordinary number of leafy branches on the sidewalk and most broadleaved evergreen trees around here are no worse for wear. Those that had the most trouble with the snow had long, slender branches, especially loquats and magnolias. Pruning to shorten these limbs (which usually causes them to become stouter) can help.

Finally, there is the complaint that they aren't available. That's also somewhat true, especially if you need a large specimen. It's an extra cost to bring up trees from California or the South for a landscape project. If you can start smaller, several sources, including our nursery, Colvos Creek on Vashon Island, offer many broadleaved evergreen trees.

Here are some of the broadleaved evergreen trees suitable for Northwest landscapes:

Arbutus menziesii / MADRONE, MADRONA

One of our most alluring natives, this tree enchants with its peeling red-orange bark. Large, glossy leaves, fragrant white flowers and bright red fruits all on a beautifully sinuous framework add up to a stunning ornamental. Sadly, the tree is very hard to transplant, though it establishes fairly easily from nursery pots. Madrones need full sun and sharp drainage and can be killed by irrigation or fertlizer. Older trees have suffered in recent decades from various blights.

Arbutus 'Marina' / HYBRID MADRONE

This newcomer is a hybrid of mysterious origin. It has foliage smaller than madrone, and showy pink flowers in fall-winter (or almost any time). Some trees bear huge orange-red fruits like those of strawberry tree (A. unedo). Bark is reddish, flaking. A small tree to 20-40 ft., 'Marina' has become popular in the Northwest, especially on streets. It wants sun and good drainage and is a good bet only in the warmer parts of the region.

Azara microphylla / BOXLEAF AZARA

With tiny, glossy leaves on graceful, airy fronds, this Chilean beauty has many admirers. Its narrow outline and quick growth make it a great screen, even between buildings. Coming from forests, it is good in shade but takes sun well; it is quite drought hardy once settled. The frosting on this cake is the crop of puffy yellow flowers in February wafting a scent of chocolate and vanilla. The variegated form 'Variegata', with cream-edged leaves, is breathtaking.

Cornus / DOGWOOD

It surprises people to learn that there are evergreen dogwoods (and maples, pears, elms, ashes, etc.) These three really do stay green and are fine small trees for milder areas. All come from south and east Asia, where there is a swarm of related evergreen species.

Cornus capitata / EVERGREEN DOGWOOD, HIMALAYAN DOGWOOD

This one stands out from the others because of its light green or grayish foliage and creamy yellow flowers. A small tree to 15-25 ft. tall, it sends its long branches artfully leaping and arching in all directions. These are covered in showy flowers that age strawberry pink over many weeks in late spring. Pink-red fruits, nearly golfball-sized, ripen in fall. Well worth a sheltered, partly shaded spot, this dogwood is hardier if raised from local seed, as ours are.

Cornus kousa v angustata / EVERGREEN KOUSA DOGWOOD

Most trees under this name are smaller, evergreen versions of the popular C. kousa. Their glossy leaves, silvery below, makes them fine foliage trees. That's good, because, so far, they have been shy flowering in the Northwest. The flowers they do produce are like those of the species, with creamy white, pointed bracts. Like the species, this variety is fairly drought-hardy.

Cornus omeiensis / MT OMEI DOGWOOD

Seen mostly in the cultivar 'Summer Passion', this dogwood is a dense, rather narrow tree to 10-15 ft. so far. New foliage, produced most of the year, is copper red. Like the dogwood above, it is also shy to make flowers, which are smaller versions of those of C. kousa. With or without flowers, this tree is a fine screen plant or small standard tree for sun or shade. It seems hardy in all but the coldest zones west of the Cascades.

Eriobotrya japonica / LOQUAT

A subtropical fruit tree with huge, leathery leaves seems an unlikely choice for the Northwest, but this Asian beauty is hardy in all the milder parts of the Puget-Willamette trough. There are trees 30 ft. tall in Portland and Seattle, and most specimens bear luscious orange fruit. Even without fruit, the foot-long, corrugated leaves make this an exotic standout. It is drought-hardy and adaptable to most soils.

Eucalyptus

These 500 plus Australian trees and shrubs have many admirers (and detractors in regions where they run wild). Their often picturesque forms and graceful, aromatic foliage combine with exotic colors in leaf and bark to produce a distinctive appeal. While most species are too tender for the Northwest, several have proven themselves here. All are very fast growing (3-10 ft. a year), drought-hardy and good in most soils, but they really need full sun.

Eucalyptus archeri / ALPINE CIDER GUM

A slender tree to 40 ft. or more before developing a wider, rounded top. Small, egg-shaped to triangular leaves of deep blue gray line green twigs; bark is flaking brown over patches of red and green. Not the most exciting species, but nice when against a dark backdrop, and very hardy.

Eucalyptus gunnii / CIDER GUM

Simiilar to E. archeri, with which it is easily confused. Cider gum tends to have pale, tan bark, white twigs and silvery leaves. It is renowned for hardiness, but is variable on that point. Most have survived recent decades here just fine. Some trees have reached 80 ft. or more.

Eucalyptus pauciflora ssp niphophila / SNOW GUM

This is likely the hardiest species. Imagine a madrone, with its curvaceous lines, but with white, cream and gray trunk and narrow, blue leaves. Snow gums reach 30 ft. fairly quickly, then more slowly develop a broad, rounded crown to 50 ft. or more. They make choice landscape features.

Eucalyptus perriniana / SPINNING GUM

Grown also for its silver-dollar juvenile foliage, spinning gum becomes a small tree 30-50 ft. high with a broad, irregular crown of willowy, blue-green leaves on red or silver twigs. The tan bark of the trunk peels in sheets; branches are smooth, satiny olive-gray. The low, sprawling habit requires plenty of room, but the tree is very hardy.

Eucryphia x intermedia 'Rostrevor'

This is the hardiest of the several evergreen species in this glorious genus of Southern Hemisphere trees. Sparkling, fine-textured foliage in soft billows cover its narrowly pyramidal form from head to toe. Fragrant white flowers resembling Hypericum open in summer. Growth is fairly fast and contented plants will reach 30 ft. tall. Such a first rate ornamental deserves wider use, though it is risky in the colder zones. It is best with partial shade and occasional watering.

Ilex purpurea (I. chinensis) / ORIENTAL HOLLY

Holly is a bad word here in the Northwest, where English holly (I. aquifolium) is such a weed. This completely innocent species, however, is still rare and deserves wide use. No Christmas holly, it is a slender tree to 60 ft. tall with narrowly oval, bright green, completely spineless leaves 3-5 in. long. The soft, lustrous foliage is very cheering in gray winter light. Oriental holly seems drought-hardy and adaptable, happy for decades in the few spots locally where it has been planted.

Laurus nobilis / BAY

This Mediterranean native is the bay of cooking. Its narrowly oval, dark green leaves are sweetly aromatic. They cover a broadly pyramidal form to 30-40 ft. tall. Some trees are very slow and haven't reached even 10 ft. in decades; others are that tall or more in five years. Bay wants good drainage, but grows well in sun or shade. It needs shelter in colder zones.

Ligustrum lucidum / GLOSSY PRIVET

A dense, rounded tree to 30 ft. or more, glossy privet presents a tailored and tony appearance. Crisp, glossy oval leaves are overtopped in early summer by lilac-like clusters of creamy white flowers. While very showy, these have the typical privet smell, which some people dislike. Tiny black fruits follow, which can lead to crops of unwanted seedlings. Snows have taken a toll on some privet trees in the past, but others have been unharmed. The tree takes drought but not temperatures below 10F.

Lithocarpus densiflorus / TAN OAK

Native in southwest Oregon and the mountains of California, this handsome tree is part oak and part chestnut. Its cream flower spikes, unpleasantly odor and all, resemble those of chestnut; the acorns in their bristly cups connect it to the oaks. Thick, 3-5 in. leaves , toothed and deeply veined, make up a narrow crown of horizontal to drooping branches reaching 100 ft. or more. This is a very worthy native, yet not much planted. It has unfortunately been the prime victim of sudden oak death, a bacterial disease that has wiped out many acres of forest in California, so many are reluctant to plant it. From the Willamette Valley north, which is well away from the infected areas, it shouldn't be a concern.